FOI was not originally intended to cover Parliament, whose own previous moves towards openness had always been on its own terms. But with the initial revelations of the expenses scandal, the FOI Act's greatest impact fell on Parliament itself, raising requests for information about MPs and by MPs themselves. Among questions asked about Parliament and MPs:

Does Parliament have a formulated policy on how to deal with paedophiles in government?

How much has a named MP claimed back on his council tax? Where did he declare his main residence?

Summary of measure/policies in place to reduce carbon emissions and recycle, or copy of guidance issued if no policy in place.

Information relating to attendance by MPs and Ministers at welcome home parades for troops.

FOI had since proved a useful tool for MPs seeking major or politically sensitive information. Examples include:

The All-Party Parliamentary Group on Extraordinary Rendition used FOI to investigate the legally dubious movement of individuals across international boundaries, linked to torture

Norman Lamb MP used FOI to obtain details of guests to the Prime Minister's country residence after a parliamentary Question in 2003 was refused. The full lists were released in the summer of 2007 and are now regularly released becoming a source of interest for the press.

In 2010 it was used by Labour MP Gordon Prentice, following an appeal, to prove that Conservative donor and deputy party chairman Lord Ashcroft broke a promise to become domiciled in the UK if ennobled.

Communities Secretary Eric Pickles used FOI against a local authority that refused to adopt his policy of publishing all spending over £500

The question remains of why so few parliamentarians chose FOI. After all, FOI has provided political ammunition for MPs and peers: the costs of the Downing Street kitchen renovation, and Tony Blair's phone calls to Rupert Murdoch before the Iraq war, are known though FOI requests made by parliamentarians. The struggle for information can be as much a news story as the information itself, and resistance isn't necessarily a bad thing if the MP can make a point out of it.

"The major problem with FOI for some parliamentarians is time and resources. FOI requests require patience and determination, especially if the government puts up a fight," says Dr Ben Worthy, the lead researcher of the study.

"Members already have Parliamentary questions, and already have direct access to the upper echelons of power. Many, especially peers, stick to the traditional methods available to them; they feel FOI might break the cordial nature of the House. FOI can be seen as an underhand tactic."

It may take a change in the way Parliament is resourced to see more parliamentarians start to use FOI. But the 2010 intake of MPs can see how effective it is already.

Notes to editors:

The report is based on a two-year project funded by the Leverhulme Trust.